Consider:

[![Enter image description here][1]][1]

Video: https://drive.google.com/file/d/1qnn96gvkQz9cFqGJDtE6-EbUUP-I_Oul/view?usp=sharing

.blend file: https://drive.google.com/file/d/1cxfsIRXvasJL4nldaWupl2wHCU-iOY-w/view?usp=sharing

I am trying to scale/extrude selected edges to the outside, but I can't. I tried:

- <kbd>S</kbd>, <kbd>Shift</kbd> + <kbd>Z</kbd>
- <kbd>Alt</kbd> + <kbd>S</kbd>

Nothing helps.

  [1]: https://i.sstatic.net/JRQEv.png